- lien son (formerly yen bail province in the far · rare gemstones from quebec. during a trip to...

Update on Colombian emerald mining. The Muzo region [Muzo and Coscuez mines) continues to be the major emerald producer in Colombia. Discovery of gem-rich veins at Coscuez early in 1992 yielded large quantities of rich, dark, well saturated emeralds, according to Ron Ringsrud of Constellation Gems, Los Angeles. This heavy production level lasted until about March 1993; production has since returned to pre-1992 levels.

Vietnamese garnets. Collectively, garnets are among the most widely disseminated gem minerals. Those of a pre- dominantly red hue have been found on every continent, including Antarctica. It should, therefore, come as no surprise that red garnets have been found in Vietnam, which has only recently begun commercial gem mining.

Saverio Repetto, of the Gemological Institute of Vietnam, a joint-venture firm located in Hanoi, sent the , ,

Gem News editors five faceted garnets for examination. According to Mr. Repetto, these stones were fashioned from rough recovered near the village of Luc Yen in Hoane Lien Son (formerly Yen Bail Province in the far - north of Vietnam, a major ruby-producing area.

The stones, ranging from 1.46 to 2.28 ct, were all very dark in tone, ii purplish red to brownish red hues (see, e.g., figure 1). The gemological properties were con- stant from stone to stone: R.1.-1.799 to 1.800, S.G.- 4.14 to 4.15, moderate anomalous double refraction when examined between crossed ~olarizers, no reaction with the Chelsea color filter, and inert to both long- and short-wave U.V. radiation. Examination with a desk- model prism spectroscope revealed strong bands at about 504, 520, and 573 nm; weak bands at 423, 460, and 610 nm; and weak general absorption below 423 nm. Magnification showed these internal features: abundant rounded-to-subrounded transparent, light yellow monazite crystals; transparent, light yellowish brown euhedral-to-subhedral phlogopite crystals; transparent, near- colorless subhedral-to-euhedral rounded crystals of apatite; zircon crystals (some displaying well-formed tetragonal symmetry) with strain haloes; dark, opaque platelets of ilmenite; and fine, short, parallel acicular rutile crystals. Using the criteria established by C. M. Stockton and D. V. Manson ("A Proposed New Classifica- tion for Gem-Quality Garnets," Gems d Gemology,

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Figure 1. These two qlmandine garnets (1.46 and 2.06 ct) are typical of material being recovered from Hoang Lien Son Province in northern Vietnam. Photo by Maha DeMaggio.

Winter 1985, pp. 205-218), we identified all the stones as almandine garnets.

Mr. Repetto informed us that red garnets have also been found in the Quy Chau District of Nghe Tinh Province, another ruby-producing area of northern Vietnam.

Myanmar mid-year Emporium. In late October 1993, one Gem News editor (RCK) attended two days of the "Mid Year Emporium, Myanma Gems, Jade and Pearl" i n Yangon (formerly Rangoon), Myanmar [formerly Burma). The entire event spanned nine days: two days of viewing and inspecting the goods, seven of sales by competitive bidding (four days of jade-614 lots, one of pearls-198 lots, and two of other gem materials-318 lots].

This emporium was the first held i n the new Myanma Gems Enterprise [MGE) exhibition hall, built adjacent to MGE headquarters solely for these bi-annual sales. In the ground-floor "Jade Display Room" (primarily one large open room), lots of rough and fashioned jade were displayed. Also offered throughout the entire event were various fashioned items at fixed prices-including all jade-related offerings under US$3,000, the lowest reserve price for jade at auction. Jade was also displayed outside, along the sides and back of the building.

Overseen by MGE officials, the actual auction took place on the second floor of the new exhibition hall.

GEMS & GEMOLOGY Winter 1993

Since bidders sat at tables in the large hall, the scene was reminiscent of a banquet. The auctioning was conducted from a raised dais at the front. As each lot was presented for bidding, pertinent inforn~ation-lot number, category of material, and reserve price-was projected onto one portion of a large screen, with a videotape of the lot itself shown alongside. When a winning bid was announced, the selling price and name of the successful bidder were also projected.

Gems, pearls, and jewelry were displayed in cases on a balcony that overlooked the auction area. Items below a certain reserve price (approximately $1,500 for pearls and $3,000 for other gems) were sold at fixed prices, as was all jewelry. This included jewelry sold on consign- ment to the MGE, as well as gem-set gold rings produced and marketed by the Myanmar VES Joint Venture Co.

Although rubies and sapphires were the most preva- lent gemstones being offered, others were available. These included amethyst, citrine, lzyanite, danburite, spinel, topaz, zircon, diopside, scapolite, apatite, aquamarine, and peridot.

Emporium officials reported total sales of $14,533,295 for 506 lots. The breakdown for auction sales was: jade (264 lots) for $5,493,173; pearls (75 lots) for $665,180; and gems (77 lo t s ) for $1,433,531. Additional sales included jewelry (quantity not provided) for $698,024; jade carvings (quantity not provided) for $69,602; fixed-price jade (five lots) for $9,300; fixed-price gems (49 lots) for $5,949,785; special-sale jade (22 lots) for $153,450; and special-sale gems (14 lots) for $61,250. The large figure for fixed-price gems includes a 38.12-ct ruby cabochon, which sold for $5.86 million. According to a report in the October 1993 Jewellery News Asia (p. 125), a ruby of this weight and measuring 18.2 x 16 x 12 mm was cut from rough found in Mogolz in 1993.

Update on Monghsu ruby. One gem material conspicu- ously underrepresented at the mid-year emporium was ruby from Monghsu (pronounced "Mong Shoo" by the Shan who live in the area and "Mine Shoo" by the Burmese and Thai). Only four small lots of stones identified as from this area, and described as "heat-treated cut ruby" in the emporium catalog, were offered at auction. All of these stones, which were examined by one of the editors (RCK), exhibited the blue cores that are distinc- tive of Monghsu material.

However, rubies from Monghsu are readily available in Mae Sai, the northernmost town in Thailand, just across the small Moei Kok River from the town of Tachileilz, Myanmar. In Mae Sai, untreated ruby rough from Monghsu is openly traded in shops and at streetside tables along what local merchants call "Soi Tab Teem," or Ruby Lane (figure 2). Here Thai dealers, most from the southeastern city of Chanthaburi, purchase stones from Burmese who cross the bridge daily between Mae Sai and Tachileilz.

Informed sources in Myanmar and Thailand described the route from mine to market as follows: Actual mining takes place at a site known as Siahlaing, about 26 k m (16 miles) southeast of the town of Monghsu. The rough is then sold at a government (i.e., legal) market about 274 km to the southwest in the city of Taunggyi. Interestingly, when some Burmese in Mae Sai were asked the source of their stones, they replied 'lTaunggyi," not Monghsu. Instead of going next to Yangon, most of the rough apparently travels east to the town of Keng Tung, from there to Tachileik, and then across the border into Thailand. The first stop there is Chanthaburi for heat treatment-to remove the typically blue-colored core zone-and cutting. Most eventually arrive in Bangkok for marketing throughout the world.


During the editor's visit to Mae Sai, several sources reported that the number of dealers had decreased signifi- cantly over the past few months. This was attributed to some controversy surrounding Monghs~i rubies and a subsequent drop in price. Fluid inclusions in the material reportedly cause some fracturing during heat treatment. The fractures, in turn, are invaded by the fire-coating substance(s) that are applied to the stones before heat treatment, resulting in inclusions reminiscent of the sec- ondary partial healing planes seen in some flux-grown synthetics. Whereas the dealers generally accept-and expect-heat treatment, they are less forgiving of the presence of such glassy, flux-like fillings deep within fractures, especially in larger stones.

Ruby in kyanite from India. International Colored Gemstone Association (ICA) Laboratory Alert No. 70 (May 17, 1993), from Elisabeth Straclz of Hamburg, Germany, reported on rough specimens of ruby in a blue matrix that was offered as ruby in sapphire. X-ray diffraction analysis, however, proved that the blue matrix was lzyanite.

Ms. Strack described the rubies as opaque, with an intense pinkish red color. Although she did not know their exact source in southern India, she speculated that they mighfbe from the area around Mysore in Karnatalza State or eve11 further south, in Tamil Nadu State. In this regard, it is interesting to note that her description of the rubies is consistent with that of the rubies and pink sapphires described in the Spring 1993 Gem News (pp. 60-61), which also were reportedly from the state of Karnatalza, about 160 lim (100 miles) south of Mysore.

Rare gemstones from Quebec. During a trip to the Canadian province of Quebec, one of the editors (EF) was loaned a number of rare gemstones from that province by Guy Langelier, a Montreal gemologist. Many pegmatites, some of which contain rare minerals that have been faceted into gemstones, are found in the Kipawa River area in southwestern Quebec. We studied a 0.36-ct orangy pink eudialyte and a 0.27-ct brownish yellow vlasovite (figure 3) from this locality.

T h e eudialyte had indices of refraction of 1.599-1.602, with a birefringence of 0.003. S.G. could not be determined precisely, because the stone was so small, but it was in the 2.81-3.12 range. The stone was inert to both ultraviolet wavelengths. The spectrum showed two sharp l ines a t approximately 521 and 572 nm. Magnification revealed a phantom plane that contained numerous groups of minute birefringent platelets (possibly mica); each associated with a dark crystal (possibly hematite) that exhibited a silvery metallic luster. EDXRF analysis confirmed the presence of all chemical elements expected for eudialyte: Na4 [Ca,Ce), (Fe+2,Mn,Y) ZrSisOZ (OH,Cl),. Traces of hafnium probably replace part of the zirconium, and traces of ytterbium, part of the yttrium.

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Potassium, titanium, and strontium were also detected. U.V.-visible absorption spectroscopy, using an Hitachi U4001 spectrophotometer, revealed a broad, iron-related absorption band centered a t about 540 nm, which accounts for the pink color. The spectrum also showed weak but sharp peaks at about 453, 461, 519, 523, 570, 579,584,594, 734, 740,750,800, and 809 nm. A compar- ison with the energy-level diagram of rare-earth ions proved these to be due to Nd3*. These lines are too weak to influence the color, but some [e.g., at 519, 523, 570, and 5791 were easily seen in the handheld spectroscope.

Indices of refraction for the vlasovite were in the range 1.609-1.624, with a birefringence of 0.015. These values are similar to those reported in the literature: 1.607, 1.623, and 1.628 (alpha, beta, gamma, respective- ly). Again, the small size of the stone prevented a pre- cise S.G. nleasurenlent, but we recorded a range of 2.90-3.26. The stone fluoresced a weak, moderately chalky, brownish orange to long-wave U.V. radiation, and a moderate yellow to short-wave U.V. It contained numerous dry fractures (some of which might be cleav-

Figure 3. The 6.02-ct. color-zoned fluorite (top) is from the Old Chelsea mine; the 0.36-ct orangy pink eudialyte (left) and the 0.27-ct brownish yellow vlasovite are from the IZipawa River area. Both areas are in the province of Quebec, Canada. Photo 0 GIA and Tino Hammid.


Figure 4. Ornamental marble from Utah, like this 42.20-ct cabochon (31.97 x 25.01 x 6.50 mm), is being promoted as "Picasso marble." Photo by Maha DeMaggio.

ages] and "undulating planes" of internal graining. No spectrum was observed with the handheld spectroscope. EDXRF analysis showed the presence of sodium, silicon, and zirconium-which are the main components of vlasovite according to its formula (Na2ZrSi40, ,)-as well as impurities of iron, potassium, and hafnium (the last probably substituting for zirconium in the structure). Despite the low R.I., there is little doubt that the material is vlasovite, since similar-appearing rough samples from the same find were identified as such by X-ray diffraction analysis.

A color-zoned fluorite from the Old Chelsea mine was faceted to produce a remarkable optical effect: Most of the stone is light greenish blue, except the dark purple culet, which reflects in almost all facets when the stone is viewed faceup [figure 3, top). Optical absorption spectroscopy showed that the light greenish blue color was caused by a wealz samarium (Sm2*) absorption at 615 nm.

Attractive ornamental marble. Among the interesting gems seen this year is an ornamental marble (a massive form of calcite] from Utah. The material has a variegated appearance, consisting of a fine-grained gray matrix with randomly oriented black and brown veining. The overall effect of the patterns is reminiscent of some abstract art; in fact, it is being sold under the trade name "Picasso marble" or "Picasso stone."

Gemological testing of a 42.20-ct oval cabochon [figure 4) revealed a spot R.I. of about 1.63 with a weak birefringence blink, The S.G., taken hyclrostatically, was 2.74. There was no reaction to long-wave U.V. radiation, and the short-wave reaction was uneven, with some areas inert and others luminescing a wealz, chalky yel-

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lowish green, The cabochon effervesced strongly to a drop of dilute hydrochloric acid. All these properties are consistent with those reported in the literature for massive calcite, proving marble to be the correct designation. The specimen did not react to an acetone-dipped cotton swab, which indicates that the material was not dyed.

Thai-Myanmar jewelry manufacturing joint venture. As noted in "Status of Ruby and Sapphire Mining in the Mogolz Stone Tract" (Gems &> Gemology, Fall 1992, pp. 154-172), the major legal outlets for Myanmar's gem wealth are the emporia now held twice a year in Yangon. Also noted were sales made through special arrangement with the government.

A newer ingredient in the marketing mix is a joint venture, established in August 1992, between Myanma Gems Enterprise and Thailand's VES Group: Mayanmar VES Joint Venture Company, Ltd. The joint venture cuts and polishes gems, and mounts them in jewelry that it also manufactures.

In addition to marketing a t the emporium, Myanmar VES currently shares retail sales space with the MGE in Yangon. According to Marketing Manager Scott Montgomery, the firm anticipates opening at least four of their own retail stores in Yangon in 1994. In late 1993, Myanmar VES had a staff of 130, which they expected to double in early 1994. Local artisans are trained by experienced cutters and goldsmiths brought in from Bangkok.

ENHANCEMENTS L

Irradiated phenomenal quartz. One novel gem seen at shows this year is cat's-eye quartz with moderately coarse, eye-visible "needles" and a dark brown, sinolzy- quartz body color that vendors reported was produced by irradiating a light gray material.

We decided to document the change in color produced in "cat's-eye" quartz (in some specimens, the "eye" is crossed by one or two weaker bands) with a greenish yellow body; this material has been known for years. We subjected one specimen to a nine-hour treatment at 1,490 kw in a nuclear reactor at General Atomics in San Diego, California. Not only did this treatment alter the body color to a very dark brown, but it also produced dis- tinct asterism in the stone. The apparent change in the phenomenon probably resulted from the higher contrast of the reflective bands against the now-dark body color.

SYNTHETICS AND SIMULANTS

Amber simulant from India. An interesting amber look- alike recently brought to our attention is called a "lac" bead (figure 5). According to the vendor, George Darveaux, these beads are produced from a natural resin in Lino Village, approximately a two-hour drive from New Delhi, India.


Figure 5. These "lac" beads (approximately 22 mm in diameter) are an amber simulant manu- factured in India. Photo by Maha DeMaggio.

The opaque beads have a swirled texture and a brownish yellow to orangy brown body color. We also noted fine surface cracks like the crazing sometimes seen on fossilized resins, Gemological examination of one sample revealed a spot R.I. of 1.51 and an S.G. of 1.67. This bead was subsequently sawn in half, revealing a medium dark brown interior streaked with a yellow material similar to that seen on the exterior. Magnifica- tion revealed that the exterior was actually a bright yellow opaque layer with a brownish orange transparent coating. These two layers have intermixed in places, so that they appear to "swirl" together. Also noted were dark brown specks of color and shallow hemispherical cavities, most likely gas bubbles that broke the surface of the outermost coating.

Artificial glass with high R.I. and S.G. Artificial glass was one of the first fabricated materials used to imitate natural gemstones. It has been produced in virtually every color and diaphaneity. Despite its range of appearances, most glass used today to imitate gems falls within a fair- ly standard range of R.I. [high 1.40s to 1.60s) and S.G. (2.30 to 4.00) values.

Since the 1950s, a number of crystalline, singly refractive materials with refractive indices over the lim- i ts of the conventional refractometer (1.8 1 +) have appeared in the gem trade. Often, these have been seen first in essentially colorless forms and used as diamond simulants; later, colored versions have appeared. Three well-known examples are YAG, GGG, and CZ. Most gemologists confronted with a relatively dense, inclusion-free, colored singly refractive material with an over- the-limits R.I. would suspect that it was one of these three simulants. For loose stones, specific gravity might be used to determine which one it probably was (typical values being YAG-4.55, GGG-7.05, CZ-5.80).

At a recent gem show, however, the editors came across material being marketed under the trade name

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'Junelite" in a range of colors, including red, blue, green, yellow, brown, and black. What caught our attention was a display card identifying the material as an artificial glass with a 2.0 R.I., a 4.59 S.G., and a hardness of about 6. Subsequent gemological testing on a 20.84-ct sawn section of blue material (figure 6) revealed that the refractive index was indeed above 1.81 and that the S.G. was 4.44. The sample also exhibited anomalous birefringence in the polariscope, which is typical of such high-R.I. materials as YAG, GGG, and CZ. X-ray powder diffraction analysis confirmed that the material was amor- phous. Gemologists are cautioned to be on guard for this material to avoid misidentifying it as YAG.

Figure 6. This 20.84-ct piece of artificial glass has an over-the-limits R.I. and an S.G. of 4.44. Photo by Maha DeMaggio.

More on Vietnamese deceptions. In recent years, the Gem Trade Lab Notes and Gem News sections have included several entries concerning the misrepresenta- tion of, synthetic rubies and ruby simulants as natural material, both rough and faceted (see, e.g., "Glass Imitating Vietnamese Ruby" in the Fall 1993 Gems o) Gemology, p. 215). On a recent trip to Southeast Asia, one of the editors (RCK) learned of other such deceptions.

While visiting the town of Yen Bai in northern Vietnam, the editor examined a number of small parcels of what was represented to be natural ruby rough from the nearby Luc Yen mining area. One notable stone- visually estimated to weigh 2-3 ct-had exceptionally good color and, based on inclusions, appeared to be a natural corundum. However, examination with a lox loupe revealed surface color irregularities. When the stone was scraped with a knife, a red coating was removed, revealing a pale pink body color.

Tony Laughter, manager of the School of Gemological Sciences in Bangkok, recounted why a gem dealer from Thailand, although well aware of ruby decep-

GEMS & GEMOLOGY Winter 1993 289

Figure 7. These two synthetic sapphires (19.20 and 29.90 at) were sold as natural sapphire rough in Vietnam. Photo by Tony Laughter.

tions in Vietnam, believed it was relatively safe to purchase two pieces of "sapphire rough" in Ho Chi Minh City: Both were color zoned, had what appeared to be iron oxide staining in fractures, and had the overall appearance and color of the blue sapphires occasionally seen from Luc Yen (figure 7). When the pieces were subsequently shown to Mr. Laughter, he determined that they were synthetic sapphires containing colorless areas and zones of curved color bands. The bands were especially evident when the specimens were immersed in methylene iodide and examined with magnification (figure 8)-

figure 8. Magnification, used in conjunction with immersion in methylene iodide, clearly reveals the curved color banding in one of the synthetic sapphires shown in figure 7. Photo by Tony Laughter.

Acknowledgments: The editors thank Gustave P. Calderon and Dino DeGhionno, of the GIA Gem Trade Laboratory, for assistance in testing materials described in the previous section.

The first International Gemmological Conference, organized by Professor K. Schlossmacher and Dr. E. J. Gubelin, was held in 1952 in Locarno, Switzerland. Since its inception, the purpose of this invitation-only conference has been the exchange of information among laboratory gemologists and others engaged in the science of gems.

The conference is hosted every two years by a different country. In October 1993, Paris was the site of the 24th International Gemmological Conference, which was organized through the Paris Chamber of Commerce by Jean-Paul Poirot. Official delegates from over 20 different countries presented papers discussing their latest research and gemological observations. Many of these papers described new gem materials, presented new tech- nical information or new ideas about previously known gem materials, or explored new gem localities. It is impossible in the space provided to discuss all of the papers read at this conference. Therefore, the following is an overview of the 24th IGC, with synopses of some of the papers presented.

DIAMONDS Canada. Canadian delegate Dr. Alfred A. Levinson gave an informative overview of the swiftly evolving diamond-exploration scene in Canada. Currently, at least 150 exploration companies are involved in the search for diamonds. Activity is particularly intense in the Northwest Territories and Alberta. In the province of Alberta alone, the area staked for further exploration is larger than that of the United Kingdom. There is also diamond exploration in eastern Canada, particularly in the Hudson Bay lowlands of Ontario.

Two major lumberlite fields have been discovered so far. The first, at Fort h la Corne in Saskatchewan, contains about 25 confirmed lzimberlites, many of which are diamondiferous. The second is in the area of Lac de Gras, Northwest Territories. It contains approximately 20 kim- berlites.

Some of the pipes discovered so far in Canada reportedly have yields of 1.25 ct per ton (as compared to the average, output for diamond pipes worldwide of 0.25 ct per ton). However, the lzimberlite samples to date have

Gem News GEMS & GEMOLOGY Winter 1993

not been large enough for definitive economic evalua- tions of either the number of carats produced or the quality of the diamonds.

India. Dr. Jan Kanis, from Veitsrodt, Germany, gave an update on the current status of gem mining and production in the State of Orissa in India, where he serves as a United Nations expert. Exploration for a possible primary diamond source in western Orissa looks promising. Not only have gem-quality diamond crystals been found by local prospectors, but microprobe analyses of pyrope and chroinite recovered in the course of prospecting also show that the chemical compositions of these indicator minerals are characteristic of those found in lumberlites and lamproites.

In addition, Orissa mines are already producing rubies of various qualities. New, commercial primary deposits of good cat's-eye chrysoberyl, cat's-eye sillin~an- ite, and hessonite have been located. As the geologic and gemological knowledge of Orissa's gem fields is expand- ed, a great similarity to the gem fields of Sri Lanka is increasingly apparent.

Green-to-blue diamonds. George Bosshart, of Lucerne, Switzerland, noted the rarity of a natural green body color-produced by the general radiation (GR) center- in diamonds. He reiterated the sensitivity of such stones to heat produced during cutting, which might induce the H3 band and those at 594 and 637 nm that could be mis- interpreted as resulting from natural annealing. He also wondered why no type Ib and type IIb diamonds with GR absorption have been reported so far.

Figure 9. A green "cloud" can be seen in this 0.24- ct natural-color green diamond. Pho~omicrograph by Nicholas DelRe; magnified 30x.

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Figure 10. Some blue diamonds, such as this 0.15- ct round brilliant, are colored naturally by irradiation and do not conduct electricity. Photo by Robert Weldon. '

Gem News Editor Dr. Emmanuel Fritsch presented new criteria for the separation of green-to-blue diamonds colored by natural irradiation from those colored by artificial irradiation. Clouds of blue or green coloration have been discovered in natural-color blue-to-green diamonds (figure 9). No such features have been observed in treated stones of similar color. Also, a particular type of U.V.-visible absorption spectrum has been found to be typical of one class of type la natural green-to-blue diamonds. Another observation is that some natural blue diamonds are colored by radiation, and these stones are not electri- cally conductive (figure 10).

History of diamond cutting. Finnish delegate Herbert Tillander, from Helsinki, briefly reviewed his compre- hensive research into the origin of certain diamond-cutting styles, the subject of his upcoming book. In his pre- sentation, Mr. Tillander focused on the development of the round-brilliant cut. He pointed out that diamond cutting was conducted in great secrecy throughout the 14th century, because religious and mythological beliefs held that diamonds could only be accepted in their natural crystal forms. Fourteenth-century diamond cutters found, however, that they could easily fool even well- educated customers simply by representing the faceted

hedral rough of any significant size, because the Indian merchants who controlled the supply were reluctant to


f w e 11, The cu L- t u w of tlae "Ha Noi - ~recious Stone Cutting a? Jewelry Factoxytt had d y a few tables in October 1992. Photo by E. AJan Jobbiss.

release octahedra. The dodecahedra, macles, and irregular shapes that were more readily available were not ideally suited to produce what today we would call the round brilliant cut.

COLORED STONES AND ORGANIC MATERIALS I Amphibolee. Dr. Hermann Bank, of Idar-Oberstein, G e r w y f reported on the discovery in East Africa of translucent, emerald-green, chromium-beamig a c u t e , which is being called "Smaragdite" in the trade. Trans- parent greenish brown magnesium pargasite, a member

Pigta-e 12. By Jan- of 1993, the cutting room of the Hanoi factory iu figure 11 was greatly essamded, with dozens of cutters using contern=

isompant. Photo by E. Alas. fobbias. - rn

oi the amphibole group, has bee& found in the EmbUipitiya gem field h Sri Lanka. Careful studies initi- atedbyDr.Bankhaveshownittobedosetothepu^e end member.

Beryl. Recent inhhg d ~ t y & red beryl in the Wah Wah Mountain& Utah, was described by Gethdid Becker, of IdarUbeistem. A new claim has probed some beau- tiful hexagonal prisms of gem and mineral-specimen quality. Slices cut from some of these crystals, both, parallel and perpendicular to the c-axis, vividly show the strong color zoning that is often present in redberyl.

Dr. Dietmar Schwm, now of Luceme, S w i t d d , provided an update on emerald-mining activity in the Ural Mountains of Russia, Egypt's eastern desert, the Swat region of Pakistan, the Ndola Rural District of Zambia, and the Sandawana area of Zimbabwe. He also described suites of solid and fluid inclusions that he h s identified dining his icsearch on emeralds from various localities.

Dr. Jan Kanh also discussed his recent visit to the Mdmgwe emerald mine in Zhbh At the time oi his visit, the open-cast mine was 70-m deep. The emer- aids produced are similar in color and quality to those found at the nearby Sandmana mine. He also mentioned reports of new emerald occurrences in Zimbabwe, approximately 40 km northeast of Sandawana.

Charoite. It was pointed out by Eugenia V. Buhtiaiova, of Moscow, in the Russian Federation, that the charoite used in the jewelry industry is actually a rock in which the main component is the mineral charoite. She therefore proposed that the name charoitite be used for this ornamental material, to signify that it is a rock and not a single d e r a l . The purple color oi &mite is a&ted to the coexistence of traces of Mna* and Fe3* (similar to +te]. When h i t e is iron rich md mmgamse poor, it is brown.

Coiund-Australiaisnotgenerallyknownasasource of color-change sapphires. In his prese~atian, however, Dr. E. Ralph Seat, ef East Malvem, Victoria, Australia, reported on a 39-ct colon-change sapphire recovered from gravels near the town of Rubyvale in Queensland. Two transparent gems, the largest being 9.17 ct, were faceted from the rough. Tile coloi of the stones in sunlight was described as olive green, while in incandescent light they appear dark reddish brown. Electron mhmpmbe d y s a earned out at the CSIRO Division of Mineral Products, Port Melbourne, showed aa iron content of 1.1 wt.%; no other trace elements wer6 detected with certainty.

Pafaape one of the best ea~amples of how the discovery of an important gean, deposit can affect the economy of an area was illustrated by E. Alan Jobbisa, of Great E ~ m b k c w ~ ~ & m d ~ h ~ u e Â¥do in Vietnam. Mr. Jobbms photographed the cutting


room of the "Ha Noi-Precious Stone Cutting & Jewelry Factory" in Hanoi, Vietnam, first in October 1992 (figure 11) and then in January 1993 (figure 12). The growth of the gem-cutting facility from a small shop to a large, well-equipped factory in just three months is visible proof of the impact that the discovery of rubies and sapphires has had.

Dr. N. R. Barot of Nairobi, Kenya, and Dr. Roger R, Harding of the Gemmological Association of Great Britain, described a new source of pink sapphire from the eastern foothills of Mount Kenya, near Kitui, Kenya. The sapphires are light to medium pink, commonly translucent, and of a quality most suitable for the fashioning of cabochons and beads. Most of the production is sold to the gem-cutting industry in India, although some of the better-quality rough is cut in Kenya or imported to Germany. The sapphires are recovered from gravels by simple open-pit mining techniques. After sieving and washing, about 50 to 100 kg of pink sapphire are recovered each week by 30-50 laborers.

Robert E. Kane, from the U.S. state of Nevada, provided an overview of various commercial and rare gems that have been found in Myanmar, both from the Moeok - Stone Tract and more recently from Monghsu. Heat Figure 13. This aerialphoto shows the "Hollandine treatment of rubies from the latter locality (to remove or mine" on the south& side of the ICunene River in diminish the. blue zoning typical of this material) often Namibia (toward the center of the lower portion of results in an attractive red, comparable to fine untreated the picture). Photo courtesy of Israel Z. Eliezri. rubies from Mogolz. Among the many so-called collectors' gems described were andalusite, kyanite, and chrysoberyl (all of which are rare from Myanmar). Mr. Kane is writing a book on the gems of Myanmar, Natural glass. Dr. Frederick H. Pough, of the United

States, presented his observations on the increasing pop- Garnet. Namibia is the source of the bright orange, trans- ularity among lapidaries of various forms of obsidian. parent spessartine garnets that are laown in the trade as Although the tumble-polished dark brown "Apache 'Hollandine" (illustrated in the Spring 1993 Gem News, tears" from Arizona are still the best-known form of p. 61). Israel Z. Eliezri, of Ramat-Gan, Israel, reported obsidian, also sought are varieties that show colorful phe- that the mine is located in a remote desert region in nomena-such as iris or rainbow obsidian (see Gem northwestern Namibia, near the Kunene ~ i v e r ( f i ~ u r e News, Summer 1993, p. 133) from Mexico, or the irides- 13). It is a nine-hour drive from the nearest settlement, cent flame or fire obsidian from Glass Buttes in central which has limited the use of heavy equipment in the Oregon. Some lapidary skill is required to bring out the mining operation to only a few pieces. The garnet crys- maximum beauty in these gem materials, but the results tals, which range up to 25 mm in diameter, are recovered can be spectacular. Although many of the inclusions that from schists. Mining operations at present take place are potentially responsible for the phenomenal effects are only on the surface, difficult to identify because they are so small, inclusions

of cristobalite and tridymite are known. Tiny acicular Meteorites with gems. Dr, Charles Arps, of the Natural crystals and hexagonal red and brown plates have also History Museum in Leiden, the Netherlands, discussed been observed but not conclusively identified; possibly the need to preserve certain meteorites in museums as they are hematite. they are found, rather than reducing them by lapidary means to pieces and sizes that are suitable for jewelry Opal. The Lambina opal field, currently classified as "dig- applications and private collectors. He is particularly con- gings," is the newest productive opal area in Australia. It cerned about the stony-iron meteorites lznown as palla- was the subject of a paper presented by Australian sites, which contain yellowish green irregular grains of Grahame Brown, coauthored by I. J. Townsend and K. olivine (see Gems es) Gemology, Spring 1992, p p 43-51). Endor. This new gem-opal field is located in a remote When gem quality, some of these peridots have been area of the Lambina Station, in the far north of South extracted from pallasite slices and faceted into small gems. Australia, about 1,000 lzm northeast of Adelaide and 360

Gem News GEMS & GEMOLOGY Winter 1993

Figure 14. This rough opal was recovered [tomth e Lambina "diggings." Th e largest piece shownis approximately 7.5 cm (3 inches) long. Photoby [ack Townsend.

km south of Alice Springs . There are two separate "diggings" at Lambina Stat ion, 2 km apart, wh ich are administered from Mintabie, a well- est abli sh ed and very productive opal field 90 km to th e southwes t. The nearesttown to the Larnbina diggings is Marla, 36 km east ofMintabie.

The precious opal from Larn bina generally occurs atdepths of 10 m or less, in joints and seams in an earlyCretaceous claystone uni t belon gin g to the MesozoicBulldog Shale. Thin veinlet s of opal are also found inoverlying jasper breccia of lat e Tert iary-early Qu aternaryage belonging to the Russo Beds . Both wh ite and blackopal are recov ered (figure 14); th e material appears to bestable [noncracking].

Certain opals seem to be m ore susceptible to crac king than others once they are rem oved from th e ground.In a paper coauthored by Mi chael Duncan, GeoffreyTombs, of New South Wales, describ ed th e results of anongoing study on the stability agains t cracking of varioust ypes of opal from different Au strali an localities .Translucent to nearly transparent "misty, " milky-lookingopal (not to be confused with white opal) with a hone ycolor in transmitted light , and mat erial that sho ws pat ches of light gray and dark gray in th e matrix, is probablynot stable and will eventua lly crack . The various wellknown forms of "preciou s" Australian opal-such asblack opal, white opal, and bould er opal- are consideredstable. The authors suggested that wat er content is onefactor in opal cracking, but not th e only one .

Porcelaneous "pearls". Kenneth V. G. Scarratt, of Bangkok,Thailand, described hi s exam ina t ion of 23 brownishorange, spherical-to-baroque porcelaneou s "pearls/ whichoriginated from th e conch Melo volut es (figure IS ). The"pearls" examined range from JJ.20 to 207 .04 ct, and up

to 32.09 mm in longest dimen sion . T he res u lts of Xradiograph y varied. Some samples showed no struc tur e,as is true of most porcelaneous "pearl s", while othe rssho wed organ ic concen tric struc tures. All displayed theflame str uc ture typi cal for non nacreou s "pearls" fromStrom bus gigas and Tridacna gigas.

Quartz. Dr. Edward J. Cubelin described and illu strated avariety of interesting inclusion s recently observed andidentified. Several facet ed gems of light pink rose quartzfrom Sri Lanka host ed a number of eye-visible transparent brownish to pinkish orange alma ndine garnet crystals; many had an unusual elongated, distorted habit (figure 16). The microscope also revea led small black grains,which proved to be ilmenite. Sma ll monazite crystalsand som e as-yet-unidentified tiny blu e acicular crystals(possibly dumortier it e?) were also see n in associationwith the included garne ts. This is a most unusual newsu ite of mineral in clusi on s for rose qu art z from SriLanka .

Figure 15. These spherical potce laneo us "pearls"grew in the Melo volutes. The largest "pearl" weighs162.99 ct and has a diameter of abo ut 28 m m. Photoby Nicholas DelRe.

294 Ge m New s GEMS & GEMO LOG Y Winter 1993

gist for identifications. In addition to the better-known synthetic amethysts and emeralds, Dr. Henn discussed

Figure 16. Almandine garnet crystals, many with an unusual elongated habit, occur with small black grainscfjlmenite in rose quartz from Sri Lanka. Photomicrograph by E. 1. Giibelin; magnified 15x.

GEMSTONE ENHANCEMENT

Professor Vladimir S. Balitsky, of Chernogolovka, the Russian Federation, explained that gemologists have been trained in Moscow only since 1978. The enhance- nient of gem materials is currently being done in Russia both experimentally and commercially. These treat- ments include irradiation of diamond, common heating of ruby and sapphire (as well as quartz), bleaching of nephrite, fracture filling of emeralds, and high-tempera- ture diffusion of sapphires. Of particular interest is the practice of bleaching rather unattractive brownish nephrite to produce a very pleasing green.

SYNTHETICS

Early synthetics. An interesting report by Dr. Henri-Jean Schubnel, of Paris, described some very unusual early synthetics in the collection of the Museum of Natural History in Paris. Not only does this collection include synthetic ruby, sapphire, and emerald grown before 1888, but it also contains pre-1888 synthetic chrysoberyl, diopside, orthoclase, and zircon.

Russian synthetics. In an overview of the gemological properties of various synthetic gemstones produced in Russia, Dr. Ulrich Henn of Idar-Oberstein addressed those features that are useful to the laboratory gemolo-

Gem News

some important and relatively new Russian synthetics, such as hydrothermally grown synthetic ruby and synthetic diamonds.

Professor Vladimir S. Balitsky also described the hydrothermal growth of phosphorus-doped synthetic rose quartz and displayed a photograph of a 1-m-wide synthetic malachite tabletop.

Dr. Gennadi V. Bukin, of Novosibirsk, Russian Federation, a specialist in both the hvdrothermal and flux , . growth of synthetic gem materials, spoke on the commercial production and marketing of emeralds made by these two techniques. Hydrothermally grown beryls in a variety of colors, flux-grown spinels (primarily red and blue), and synthetic alexandrite produced by both flux and melt techniques are also grown commercially in the Design Technological Institute of Monocrystals in Novosibirsk. Dr. Bukin reported that they have grown synthetic alexandrite by the hydrothermal method, but only experimentally. Using the hydrothermal method, they are also able to heal fractures in natural emeralds.

Douros flux-grown synthetic ruby. Dr. Henry A. Hanni of Zurich, Switzerland, working with Dr. Karl Schmetzer of Germany, presented the results of their preliminary examination of the new Greek flux-grown synthetic ruby being marketed under the trade name Douros. In crystal form and as cut stones, from a gemological standpoint, these new synthetic rubies closely resemble the Ramaura flux-grown synthetic rubies. Chemical analysis showed a variable trace-element composition in the Douros material, with no characteristic chemical profile. The major trace elements found in natural rubies-chromium, galli- um, iron, titanium, and vanadium-are also added in variable amounts to the Douros synthetic rubies. Dr. Hanni concluded that, if inclusions and recognizable growth structures are not present, this new synthetic ruby will be extremely difficult to identify.

INSTRUMENTATION

In a paper coauthored by Guerec Querrk and Jean-Paul Poirot, Dr. Anne Bouquillon, from the Laboratoire de Recherche des Musees de France, at the Louvre Museum, described some very interesting work on gem-set gold Egyptian pectorals from the Louvre collections. PIXE (Proton Induced X-ray Emission) analysis with a particle accelerator was used to determine the chemical compositions of the gem materials and metal. In the course of their study, these researchers found a type of manufac- tured gem material known as "frits," which is composed of a mixture of lapis lazuli and silica powders.

Jean-Marie Dereppe, of Belgium, presented information on the application of nuclear magnetic resonance (NMR) to gemological problems. He discussed the separation of natural from synthetic emeralds using this tech-

GEMS & GEMOLOGY Winter 1993 295

Figure 17. This laser-tomogruphic image of a 0.68- ct synthetic ruby shows the growth banding characteristic of flame-fusion synthetics as well as the treatment-induced "fingerprints" that result from flux overgrowth. Photo courtesy of h n k o Shida.

nique. He speculated that NMR might also be useful in the separation of natural from heat-treated aquamarine, which currently is virtually impossible to do.

Professor Bernard Lasnier, from the University of Nantes, presented two new instruments of interest to gemologists. The first was a desktop Raman spectrometer. While the performance level of such instruments has gone up in recent years, the price has come down consid- erably, making this type of technology much more affordable. This spectrometer will soon be adapted to a microscope, so it can also be used in nondestructive inclusion identification. Professor Lasnier also showed a small brass "Pearlscope." This combination endoscope- lucidoscope, hand-made by one of Professor Lasnier's stu- dents, Har Hatalay, in demonstration worked well in showing the difference between drilled natural and cul- tured pearls. Mr. Hatalay is investigating the economic feasibility of producing a small number of these instruments for the trade.

Dr. Karl Schmetzer presented his latest observations on the use of immersion nlicroscopy in the examination of microscopic growth structures in rubies to determine natural or synthetic origin. He compared growth features in rubies from Monghsu in Myanmar to those in rubies from Luc Yen in Vietnam. The growth structures of the new Douros flux-grown synthetic rubies, produced in Greece, were found to be very similar to those of the well-known Ramaura flux-grown rubies, produced by Judith Osnler in California.

Gem News

Observation of rubies and detection of heat treatment by means of laser tomography was the subject of a paper presented by Ms. Junlzo Shida, of Tokyo, Japan. Using a laser beam as a light source, laser tomography is an optical method to record on film the distribution of scattering centers (such as submicron-size and larger inclusions), as well as features such as growth banding, in crystalline solids like gemstones. One advantage of laser tomography in gem identification is that even submicron scattering centers are visible at low magnification. For example, the laser-tomographic image (shown in figure 17) of a 0.68-ct synthetic ruby clearly illustrates both the curved growth characteristics of a flame-fusion product and the pattern produced by treatment-induced flux fingerprint inclusions resulting from overgrowth. Further studies are planned using this technique to examine and visually document rubies both before and after heat treatment.

Using petrographic analysis and thermobarometric techniques, Dr. John M. Saul and Alain Mercier, both of France, studied the metamorphic primary ruby deposits of the Precambrian Mozambique Belt in southeastern Kenya. They determined that the rubies crystallized at approximately 750Â° under a pressure of about 5 kbar. This relatively low pressure indicates that the rubies formed at a depth of approximately 17 km. With this same methodology, other gem deposits could be examined to determine depth of formation and possibly the vertical extent of mineralization.

MISCELLANEOUS

Early collections. Dr. Pieter Zwaan, of the Netherlands, described a collection of 625 gems that King William the First donated to the National Museum of Natural History, Leiden, in 1825. Such collections of known age are of particular gemological interest because the stones reveal what forms of gem treatment were used before a particular point in history. In this collection, the only stones that were treated were chalcedony.

Colored stone cutting. A videotape prepared by Menahem Sevdermish, of Israel, compared the skills and products of Indian and Sri Lanlzan gem cutters to the production of the sophisticated and highly automated cutting facto- ries in Israel. Mr. Sevdermish concluded that technology has not yet replaced truly skilled hand labor in terms of quantity and quality in the fashioning of gemstones.


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